澳大利亚布劳斯盆地深水区Jamieson组AVO异常成因分析

Origin of AVO anomaly of Jamieson Formation in deepwater area of Outer Browse Basin, Australia

针对澳大利亚布劳斯盆地深水区钻探的失利,通过目的层Jamieson组岩心薄片鉴定,结合区域沉积环境分析,对该区深水区钻探进行了综合分析。结果表明:这套硅质岩和硅质泥岩的特殊岩性体中富含放射虫与硅藻,且虫体内微孔隙发育,由于处于成岩演化的早期B阶段,微孔隙得以保存,使岩石具有高束缚孔和低密度的特征,从而产生了测井上的"含气砂岩"特征和地震上的AVO异常。类似的AVO异常并不少见,尤其是在深水浅层沉积中,而事实上这类异常是由岩性造成的,并不表示含气,因此,今后的深水区勘探应注意规避此类风险。

Based on core thin seetions analysis and regional sedimentary settings, this paper carried out a comprehensive analysis of the exploration of Jamieson Formation inW-I well in Outer Browse Basin, Australia. The resuh shows that Jamieson Formation is a set of Aptian-Cenomanian biosilieeous rock to be of rich radiolarians and dialoms, and micro- porosity developed inside the foraminifer. The biosilieeous rock is al a phase of early diagenetie B belween opal A to opal CT transition with substanlive mieropores survived and is of high-bounded porosity and low density. The false gas- bearing reservoir in CMR log and AVO anomaly are eaused by sueh petrographie eharaeteristies. In fact. the biosilieeous rock of Jamieson Formation is poor reservoir. Similar eases with false-DHI are not uncommon, especially in the shallow targets in deepwaler and should be lake notice of exploration.